Bones ch 6

bone remodeling

ongoing replacement of old bone tissue by new bone tissue

lipid storage

yellow marrow

spongy bone

(cancellous bone) -located where bones are not heavily stressed -trabeculae -no central canal -site of red marrow

compact bone

- dense, hard -diaphyses of long bone -outside edges of epiphyses and irregular bone -made up of osteons

composition of osseous tissue

- ~50% collagen fibers and ground substance - ~50% calcium and phosphorus

Osteons

-Cylindrical structures -vascular -compose compact bone

intramembranous ossification

-mesenchyme (stem) cells transform to osteoblasts in connective tissue -most flat bones in skull

endochondral ossification

-replaces hyaline cartilage with bone -growth in puberty - forms most bones Long bone Development

Functions of the skeletal system

-support -protection -hematapoiesis -mineral homeostasis -lipid storage -movement

endochondral ossification process

1. fetal hyaline cartilage model of bone develops 2. cartilage calcifies and a periosteal bone collar forms around diaphysis -chondrocytes enlarge within shaft and resorb part of cartilage -cartilage undergoes calcification -chondrocytes die, leaving hardened matrix -at the same time, perichondrium is invaded by blood vessels -cells in perichondrium turn into osteoblasts -periochondrium transformed into periosteum -periosteal bone collar formed 3. primary ossification center forms in diaphysis 4. secondary ossification centers form in epiphyses 5. bone replaces cartilage, except the articular cartilage and epiphyseal plate 6. epiphyseal plates ossify and form epiphyseal lines

Movement description

attachment site for muscles

mineral homeostasis description

calcium and phosphorus

trabecular bone (spongy bone) V.S. compact bone

compact bone is hard and less porous -located under periosteum and in diaphyses of long bone trabecular bone is soft and porous -located at the ends of long bone

central canal

contains blood vessels and nerves -found in osteons

Epiphyses

ends of long bone

support description

lower body supports upper body

trabeculae

network of thin tubular bone structures

protection description

protects organs

Hematapoiesis description

red bone marrow

Lamellae

rings around the central canal -sites of lacunae

bone deposition

the addition of minerals and collagen fibers to bone by osteoblasts

diaphyses

the main midsection, or shaft, portions of long bones; each contains a medullary cavity

bone resorption

the removal of minerals and collagen fibers from bone by osteoclasts